class User1{
    public readonly name:string;
    private age:number;
    protected group:string;
    constructor(name:string,age:number){
        this.name = name;
        this.age = age;
        this.group = 'admin';
    }
    public getAge(){
        return this.age;
    }

    changename(){

    }
}

const u1 = new User1("wangwu",18);
// u.name = '12';
u.getAge();
u1.changename();

class Person extends User1{
    constructor(group:string){
        super("",21);
        this.group = group;
    }
}
